Back in the day, I had an avid ground hog hunter friend turn me on to 223 'goffer loads" made up with Blue Dot shotgun powder. These loads were much quieter than standard 223 loads as all the powder would be burnt in 16" of barrel. ( Low bark and flash) POI of a 40gr bullet moving at 2300 fps was plenty for the critters and within an inch of the factory stuff at 100 yds too. Very sweet and useful loads that he shot by the hundreds on the farm he had permission to hunt. You might look into something like that for your buddies situation.
FWIW, Recently I've been reloading 120gr bullets in 6.5CM using H4895 at a 75% max load. (4895 is one of the few powders that can be loaded in lower quantities in most cartridges down to 65% ish of max range without fear of detonation. These are very pleasant loads that I use for punching paper out to 300 yds. At 100 yds, I get 1/2 MOA with them.